<!DOCTYPE html>
<html>

<head>
    <meta charset="utf-8">
    <title>在线尝试 Bootstrap 实例</title>
    <script src="http://libs.baidu.com/jquery/2.0.0/jquery.min.js"></script>
    <script src="http://libs.baidu.com/bootstrap/3.0.3/js/bootstrap.min.js"></script>
    <link href="http://libs.baidu.com/bootstrap/3.0.3/css/bootstrap.min.css" rel="stylesheet">
</head>

<body>
    <h1>Hello, world!</h1>
    <h2>下拉菜单</h2>
    <!-- 下拉菜单 -->
    <div class="dropdown">
        <button class="btn btn-default dropdown-toggle" type="button" id="dropdownMenu1" data-toggle="dropdown" aria-haspopup="true" aria-expanded="true">
            Dropdown
            <span class="caret"></span>
        </button>
        <ul class="dropdown-menu" aria-labelledby="dropdownMenu1">
            <li><a href="#">Action</a></li>
            <li><a href="#">Another action</a></li>
            <li><a href="#">Something else here</a></li>
            <li><a href="#">Separated link</a></li>
        </ul>
    </div>
</body>

</html>
